The global construction of industrialization and informatization raises a high demand on the AC-DC rectifier power supplies. In the field of high-medium power, with the advantages of strong adaptability, high reliability, strong shock resistance and load capacity, the power-frequency AC-DC rectifier power supplies have been widely applied to various industries. However, large grid-side current harmonic of the power-frequency AC-DC rectifier power supplies results in very serious pollution to the power grid. Furthermore, the current high-power power-frequency AC-DC rectifier can meet the requirements of use of the power grid only when configured with devices related to power grid compensation.
In order to solve the problem of power harmonic pollution resulted by rectification on the input side of the traditional high-power power-frequency AC-DC rectifiers, high-power systems generally employ a structure formed of a full-isolated phase-shifting transformer based on “Δ/Y and Δ/Δ type” and an additionally balancing reactor. The 12-pulse rectifier technology is achieved by two traditional 6-pulse phase-controlled rectifiers with a phase shift of 30 degrees, thereby suppressing 5 and 7 harmonics generated by a three-phase six-pulse rectifier. However, this manner has problems that the isolated phase-shifting transformer is bulky, heavy and high in cost, and is not convenient for the extension of the higher power AC-DC rectifier system.